The present invention relates generally to distortion suppression techniques, and more particularly, to a nonparametric distortion suppressing technique operable in the time and frequency domains that provide improved communication signal reception without knowledge of the distortion characteristics.
Prior art techniques that suppress interference include two major types: frequency domain and time domain. Existing frequency domain interference suppressors typically utilize adaptively controlled notch filters to suppress or excise narrow band interference. Practical versions of these filters have fairly wide notch widths, typically 2% to 10% of signal bandwidth, and require a significant adaptation time. Consequently, their preciseness of excision is severely limited, especially for multiple interference frequencies, and their long adaptation time makes the excision process vulnerable to swept or blinking jamming.
Existing time domain interference suppressors include receiver blankers, limiters and automatic gain control circuits. If the received interference power can exceed the damage threshold of the receiver front-end components, a protective blanker or limiter is needed to avoid damage. Also, a blanker or limiter may be needed in order to reduce or avoid receiver saturation recovery time. Prior art blanker and limiter circuits intended exclusively for these purposes are essentially transparent to antenna outputs below a critically high level.
Accordingly, it is an objective of the present invention to provide a distortion suppression technique that overcomes the limitations of conventional techniques and that is applicable to both time and frequency domain signal processing.